1. Field of the Invention
The present invention relates to a medical method and apparatus whereby an umbilical cord can be stabilized by being held against an interior surface of the uterine wall, and whereby medical procedures can be performed on said stabilized umbilical cord.
2. Description of the Prior Art
Percutaneous umbilical cord blood sampling has become an accepted procedure for evaluation of certain complications in high risk pregnancies. Direct fetal blood sampling has been used to evaluate fetuses with hemolytic disease of the newborn, various fetal viral infections, fetuses at risk for chromosome aberrations, as well as for evaluation of certain biochemical parameters within the fetus. In addition, percutaneous cordocentesis (puncture of the intrauterine umbilical cord with a needle) has been used extensively for intrauterine transfusion of fetuses affected with hemolytic disease of the newborn due to feto-maternal blood incompatibility.
The technique of cordocentesis involves using realtime sonography to guide a fine gauge needle into an umbilical vessel, usually the umbilical vein. In the case of an anterior placenta (i.e., placenta implanted on the anterior uterine wall), the prior art comprised passing the needle transplacentally into the placental attachment of the umbilical cord. By doing so, one could avoid trauma to the puncture site caused by fetal movement. In the case of a posteriorly implanted placenta, the prior art comprised guiding the needle through the anterior abdominal wall and amnionic cavity into the placental attachment of the umbilical cord on the posterior uterine wall. In the event that the cord insertion of a posteriorly implanted placenta could not be visualized, the site recommended for cordocentesis has been the fetal attachment of the umbilical cord. Various authors have documented inherent dangers caused by fetal movement with either of the latter two recommended procedures. Complications have ranged from inconvenience, with the needle becoming dislodged, to catastrophic, in that a rent in the umbilical vein was caused by sudden fetal movement leading to fetal exsanguination and death.
The inventor has observed cases in which there was placental complication of percutaneous cordocentesis for intrauterine transfusion in the treatment of hemolytic disease of the newborn. In one case, when an anterior placenta was traversed in an attempt to enter the transplacental attachment of the umbilical vein, a vein on the surface of the placenta was transected and a large hematoma resulted, which was noted at delivery. In another case there was a velamentous insertion of the umbilical cord (insertion of the fetal umbilical cord into the lateral margin of the placental through the membranes instead of into the central portion of the placenta). Several attempts were made to puncture the fetal umbilical vein and at one point the vein was inadvertently torn, a large hematoma developed, and the fetus subsequently expired. The hematoma was confirmed at the time of delivery. See Berkowitz, et al., Intrauterine intravascular transfusions for severe red blood cell isoimmunization: Ultrasound-guided percutaneous approach, Am. J. Obstet. Gynecol. 574, September 1986.
Recently, investigators have discovered that transplacental cordocentesis may actually elevate maternal antibody titers in patients with pregnancies complicated by isoimmunization. It would appear, therefore, that transplacental sampling through an anterior placenta may indeed be deleterious.
The above discussion points out the need for a method to access the umbilical vessels without traversing the placenta and without subjecting the umbilical cord to a risk of tearing due to fetal movement. This invention discloses such a method and an apparatus that is used to accomplish the method.